Vertical machining center

A vertical machining center comprising:

• a base;
• a splash cover fixed to the base, the splash cover defining a machining chamber to enclose a machining zone and to separate from a non-machining zone, the splash cover including:
• a peripheral cover surrounding the machining zone,
• an upper side cover disposed on an upper side of the machining zone, the upper side cover being joined to the peripheral cover,
• a back side cover disposed on a back side of the machining zone;
• the back side cover having a right back cover and a left back cover;
• a column fixed to the base and vertically standing on the base, the column having a recessed part and being positioned between the right back cover and the left back cover, the column having a right side surface to which a left end part of the right back cover is joined, and a left side surface to which a right end part of the left back cover is joined, a right end part of the right back cover being joined to a right end part of the peripheral cover, a left end part of the left back cover being joined to a left end part of the peripheral cover, the right back cover and the left back cover being joined to the upper side cover;
• a Z-axis guiding rail disposed on the column and being vertically directed toward the base, the Z-axis guiding rail being partially exposed to the machining zone;
• a Z-axis driving device disposed in the recessed part of the column, the Z-axis driving device being partially exposed to the machining zone;
• a spindle head to be guided by the Z-axis guiding rail and to be driven vertically by the Z-axis driving device;
• a spindle head opening formed in the upper side cover of the splash cover so that the spindle head can pass through the spindle head opening;
• and
• an extendable cover provided between an edge of the spindle head opening and the spindle head, the extendable cover being configured to cover parts of the Z-axis guiding rail and the Z-axis driving device, the parts being exposed to the machining zone in a case where the extendable cover does not cover the parts.